Properly init pointer when no avx2

commit_hash:9c39c2ba0ff9c555e6f5da0bbe3d8be5a04d6654

Author: eivanov89

library/cpp/dot_product/dot_product.cpp

@@ -37,6 +37,7 @@ namespace NDotProductImpl {
                 DotProductI32Impl = &DotProductSse;
                 DotProductFloatImpl = &DotProductSse;
                 DotProductDoubleImpl = &DotProductSse;
+                TriWayDotProductImpl = &TriWayDotProductSse;
 #endif
             }
             return 0;